Circuit breaker



R E T A S G. M

Jan. 2s, 1941.

,R E K A E R B T I U C R I C Filed Nov. 2l, 1934 MTM INVENTOR WITNESSES:

ATTORN Patente# Jan. 28, 1941 PATENT OFFICE CIRCUIT BREAKER Manin c.stieren, west springfield, Mass., assignor to Westinghouse Electric tManufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application November 21, 1934, serial 1go. 754,932

16 Claims.

My invention relates generally to circuit interrupters and particularlyto electrical switching devices which utilize mercury for opening andfor closing the electrical circuit therethrough.

The principal object of my invention is to provide an improved mercuryswitch which shall be more rugged in design, more reliable in operation,and less expensive to manufacture than the previously known devices ofthis type.

Heretofore, most oi the mercury switches which have been known to theart have utilized a glass tube or casing for enclosing the mercury andhave .been provided with suitable actuating means for tilting this tubein order to operate the switch. There are numerous disadvantages in theuse of glass casings, the most important of which, perhaps, is thefrangibility of that substance. Despite this, however, glass closureshave been widely used, particularly in those applications where it wasfound desirable toprovide a liquid or gaseous medium for aiding inextinguishing such arcs as may be formed during the operation of theswitch.

It would appear that the most desirable form of mercury switch wouldinclude an unbreakable casing which might be made absolutely gas tight.One of the most likely materials for such a casing would, of course, bemetal, but heretofore no satisfactory means has been found for providinga metal casing for mercury switches which could be made gas-tightwithout unreasonably large expense. And even in those switches whichhave utilized metallic casings, it has been found necessary to include aceramic or other frangible insulating means for a portion of that casingin order to separate and insulate the switch electrodes from each other.

My invention, however, provides means whereby a metallic casing may beutilized for a mercury switch or similar device, in such manner that asubstantially unbreakable structure is produced. It also provides meansfor completelyvsealing the casing of the switch in order that a gas orother medium may be introduced therein for aiding in D the extinction ofsuch arcs as may be established during the normal operation of theswitch.

The complete enclosing of the structure of my invention is rnadepossible primarily through the provision of an improved seal whichutilizes a means of resilient insulating material for insulating one ofthe electrodes from the metallic Vcasing and for providing a gas-tightseal between that electrode and the casing.

A further object of my invention is to provide a mercury switch whichshall utilize a metallic (Cl. ZUG-152) casing for one of the electrodes,and which shall be provided with means of refractory material for aidingin the extinction of the arcs whichv are established during theoperation thereof.

A still further object of my invention is to provide a mercury switchwhich shall be substantially shock-proof, and which may be manufacturedwithout the use of"`any complicated apparatus.

These and other objects of my invention will be made more apparent n thefollowing description ofa preferred embodiment of my invention.Referring to the single sheet of drawings:

Fig. 1 is a sectional view of a mercury switch constructed according tothe principles of my invention;

Fig. 2 is a sectional view on the line II-II of Fis- 1;

' Fig. 3 is a sectional view on the line III-III of Fig. 1; ft

Fig. 4 is a sectional,- view on the line IV-IV of Fig. 1; and

Fig. 5 is a view partially in elevation and partially in section,illustrating a modified sealing means which may be used with the switchshown in the other figures of the drawing.

The switch illustrated in Figs. l` to 4 comprises, essentially, an outershell".or casing I which is spun or otherwise formed from a single pieceof metal and which is adapted to `serve as one of the electrodes of'theswitch. A "second electrode 3 is disposed within this casing andisinsulated therefromby a sealing means 5 which includes a member 1 ofresilient insulating material. This member 1, in the complete device,has the further function of providing a gas-tight seal between thesecond electrode 3 and the casing I. An annular member 9 of refractorymaterial, preferably porcelain, is positioned within the outer casing Iand has a shoulder that provides an arc resistant surface upon which thearc incident to the opening of the electrical circuit through theswitchfis established.

More specifically, the outer casing I comprises a pair of concentrictubular, members I0 and I2 which are of dissimilar diameters and whichare joined together at one end so as to form a continuous passageway.The left-hand end of the smaller tube I0 ls closed at all times by anend portion II which is either formed integral therewith or is rigidlyaiiixed thereon by any of the well known means to make the -tube ID acupshaped member. The junction of the larger and the smaller tubes formsan annular shoulder I3 which is adapted to serve as aV support for themember 9 of refractory material, and, through I as the opening withinthat member, for the electrode and sealing means. A quantity of mercury,which separates into two pools Il and I6 when the switch is in the opencircuit position, is contained within the casing I for effecting theopening and the closing of the electrical circuit through the switch.

The electrode 3 consists of a rod-like member or stein portion,preferably of steel, which terminates in an enlarged head portion I5having substantially the same outer dimensions as the larger opening I1within the annular member of refractory material. cut away in order toprovide a pocket or recess I9 for retaining the smaller of the two poolsof mercury and for facilitating the opening of the switch, the opening20 within the annular member 9 being somewhat smaller than the cut awayportion I9 in order to aid in retaining the smaller mercury pool I6 inthe position shown.

The sealing member 1 has the formol a hollow cylinder of substantiallythe same outer diameter the larger of the two tubes, and in order tofurther facilitate the sealing operation the central openingtherethrough has substantially the same cross sectional dimensions asthe rod portion of the electrode 3. The left-hand surface of the sealingmembe is adapted to abut against the right-hand surface of the enlargedportion I5 of the electrode and the right-hand surface of. the annularmember 9, and a flat circular plate 2|, of a rigid, mechanically stronginsulating material, is disposed at the right-hand surface of the mainsealing member 1 in order that suiiicient force may be transmittedthereto to secure a gas-tight seal between the electrode and the casing.

During the assembling of the switch, the righthand end of the largertube I2 is open. The annular member 9, the electrode 3, the sealingmember 1, and the plate member are inserted through this opening, in theorder named, following the placing of the mercury in the bottom of thecasingl then the outer edges of the right-hand portion of the largertube I2 are spun so as to subject the resilient sealing member 1 to adeforming stress of sufficient magnitude to provide a gastight seal. Aspace 22 is left between the casing and the electrode in order to avoidshort circuiting of the switch. The resultant structure is substantiallyunbreakable and, if desired, it may, during the manufacturing operation,be lled with any suitable gas or fluid, at a pressure either less thanor greater than atmospheric, the seal 5 assuring that no leaks shalloccur during the normal operative life of the device. If desired,gaskets (such as those shown at 23 and 25) may be utilized forequalizing the stresses on the annular member 9.

In the preferred form of my invention, I utilize a body of syntheticrubber for the main sealing member 1. This substance has numerousadvantages over the other known resilient insulating materials in thatit is quite resistant to mercury vapor, and thus assures the maximumoperative life of the switch. Ordinary rubber may also be used withreasonable success, as may certain other resilient insulating substancesand compounds.

'I'he annular refractory member 9 is preferably constructed of porcelainchiefly because that material is comparatively inexpensive. Otherrefractory materials are equally suitable, and it is also possible, insome instances desirable, that the shape of this member be other thanthat shown in the drawing. For example, if it is desired to in- Theinner end of this portion is crease the arc rupturing capacity of theswitch, it may be desirable to provide a sleeve extension on to thisrefractory member which would extend into the smaller of the two tubeslor a greater or less distance.

Soft steel has been found particularly suitable for use in forming thecasing of the switch, it being possible when using this material to spinthe entire casing from a single sheet of metal. Other materialsv are, ofcourse, suitable for this purpose, and itis not necessary or imperativethat the entire casing be spun. l

It is also within the province of my invention that the deforming stresswhich is imparted to the sealing member 1 may be produced by means otherthan spinning over the outer edge of the tube. The spinning method isparticularly preferable, however, because of its low cost.

In certain installations it is highly desirable that the switch beentirely water-proof, and my invention lends itself particularly to thisform. As illustrated in Fig. 5, it is easily possible to vulcanize abody 21 of rubber or rubber compound over the main body of the casingand over the end thereof which is open following the spinning operation.This assures a water-proofing of the entire switch, and is, of course,of great value in certain applications.

For those installations wherein the gaseous medium contained within themain closure is at a pressure considerably above or below atmospheric,it may be desirable to vulcanize the sealing member 1 to the electrode 3and the adjacent portions of the larger tubular member I2. If a steelcasing and a steel electrode are employed it may be found necessary, forbest results in this operation, to plate the surfaces which contact themember 1 with brass, this metal being capable of adhering particularlywell to vulcanized sulphur-free rubber. A vulcanized seal is, a perfectseal than one which depends upon pressure for its efficacy, but itsincreased expense usually limits its use to certain specialapplications.

The switch is operated in a manner similar to other mercury switches,that is, by tilting the outer casing in order to cause the mercury tomove from the open circuit position illustrated in Fig. 1 to a positionwhere 4the two pools Il and I6 contact each other. No mounting oroperating means has been shown, because numer-v ous arrangements of bothtypes are well known in the art.

In order to aid in the extinction of such arcs as may be establishedwithin the device, I prefer to lll the space between the outer casingand the electrode with a low atomic weight gas which is chemically inertto mercury vapor. Hydrogen is particularly suitable when used under apressure of about 11/2 atmospheres, this pressure assuring thatexistence of small leaks will not result in contamination of the arcextinguishing medium within less than a very considerable period oftime. Helium is also suitable and certain other inert gases may beutilized with reasonable success.

From the foregoing, it will be seen that I have provided a mercuryswitch which has numerous advantages over the devices heretofore knownin the art. My improved switch is practically unbreakable. It may beassembled by an ordinary mechanic without the use of any complicatedglass-blowing or sealing equipment, and low in cost. Further, by

despite this it is very of course, more nearly A Cai may be made gasandliquid tight.

As a feature of my improved switch, I have' disclosed anew form ofgas-tight seal which is applicable not only to mercury switches but toother devices generally. I have also shown how my improved seal may beutilized for insulating and positioning an electrode within a piece ofelectrical apparatus, thereby reducing the cost and simplifying thestructure of that device.

While. in accordance with the patent statutes. I have disclosed ltheforegoing details of a preferred embodiment of my invention, it is to beunderstood that many of these details are merely illustrative and thatvariations of their precise form will be both possible and in someinstances desirable. I desire. therefore. that the language of the'accompanying claims shall be accorded the broadest reasonableconstruction. and that my invention shall be limited only by what isexpressly stated therein and by the prior art.

I claim the following as my invention:

l. In a switch having a conducting fluid for completing the circuit. ametallic casing which serves as one of the electrodes of said switch, anopening formed in said casing, an electrode extending through saidopening into said casing. means providing a stop for determining thepoint to which said electrode may extend into the casing, and` means forpositioning said electrode within said opening against said stop meansand for forming an insulating, gas-tight seal between saidv electrodeand said casing. said l seal forming means including means of resilientinsulating material and means for placingy said means of resilientmaterial under a suitable deforming stress. l

2. In a switchQa metallic casing. an electrode extending into saidcasing, a body of conducting uid in the casing for completing theelectric circuit through the switch, means of resilient insulatingmaterial between said casing and said electrode, a pair of spacedabutments extending inwardly from the wall of the casing and providing aforce placing said means of resilient insulating material incompression, thereby providing a seal between said electrode and saidcasing. l

3. In a switch,`a metallic casing, an electrode extending into saidcasing, a body of conducting fluid in the casing for completing theelectric circuit through the switch. meansl of resilient insulatingmaterial between said casing and said electrode, a pair of spacedabutments extending inwardlyl from the wall of the casing and providinga force placing said means of resilient insulating,Vj material incompression, and means for distributing said force over a major part ofthe area -of said means of resilient insulating material, therebyprovidingv a seal between said electrode4 annsaid casing.

4. A conducting fluid switch comprising a metallic casing which is'provided with an opening formed therein, an electrode extendingvthrough said opening intdi` said casing, said casing serving as theother electrode, means of hard retractory insulating material forpositioning and spacing said electrode within said casing, and a singlemember of relatively soft resilient insu lating material extendingacross and sealing said opening in said casing through which saidelectrode extends and positioning the means of refractory material inthe casing.

5. A conducting-fluid switch comprising a. me-

tallic casing which serves as one of the electrodes of said switch andwhich is provided with an opening formed therein. an electrode extendingthrough said opening into said casing, means of refractory insulatingmaterial disposed within said casing for positioning said electrodetherein and for providing an arc resistant surface across which the arcincident to the circuit opening operation oi said switch is drawn, and asealing member of a material which is composed, at least in part, ofresilient rubber-like material for positioning said means oi refractorymaterial in the casing. for insulating said electrode from said casingand for providing a seal extending between said electrode and said cas?ing.

5. A mercury switch comprising a metallic casing which serves as one olthe electrodes of Said switch and which is provided with an openingformed therein. an electrode extending through said opening into saidcasing, means of refractory insulating material disposed within saidcasing for positioning said electrode therein and for providing an arcresistant surface upon which the arc incident to the circuit openingoperation of said switch is drawn, and `Vmeans for forming a gas-tight,insulating seal between said electrode and said casing. said sealforming means including means of resilient insulating material andspaced parts extending inwardly from the casing for exerting a forcecompressing said meansv of resilient insulating material at points closeto said electrode.

7. In a switch having a conducting iluid for completing the circuit, ametallic casing, an opening formed in said casing, an electrodeextending through said opening into said casing, an abutment in saidcasing, a member of resil-` ient insulating material disposed about atleast a portion of said electrode adjacent said opening for insulatingsaid electrode from said casing and for closing said opening, meansadjacent said opening for forcing said resilient material toward saidabutment and placing said resilient material under a suficient deformingstress to provide a gas-tight, insulating seal between said casing andsaid electrode.

8. In a mercury switch, a tubular metallic casing which serves as one ofthe electrodes of said switch, one end of said casing being normallyclosed at all times and the other end being open during themanufacturing of said switch, an electrode extending through saidopening end into said casing, an abutment in said casing, and a memberof resilient insulating material disposed about at least a portion ofsaid second electrode adjacent said open end for insulating saidelectrode from said casing and for closing said opening, the outer edgesof the open end of said tubular means being in-turned and forcing saidnumber of resilient material toward said abutment and subjecting saidmember of resilient material to a suiiicient deiorming stress to providea gas-tight. insulating seal between said casing and said electrode.

9. In a switch, a metallic casing, an electrode extending into saidcasing, a body of conductinguid in the casing for complet-ing theelectric circuit through the switch, means of resilient insulatingmaterial between said casing and said electrode, a ridge on the innerwall of the placing said means of resilient insulating material and saidelectrode in compression between said ridge and said spun-over end,thereby procasing and a spun-over end on said casing for` viding a sealbetween said electrode and said casing.

10. In a switch, a metallic casing. an electrode extending into one endof said casing, a body of conducting fluid in the casing for completingthe electric circuit through the switch, means on the inner wall of thecasing providing a stop, means of relatively soft resilient insulatingmaterial in the space between said electrode and casing, means ofrelatively hard insulating material between said means of relativelysoft insulating material and the end of the casing, and means on the endof the casing for applying a force to said means of relatively hardinsulating material and thereby forcing said means of relatively softinsulating material toward said means providing a stop for deformingsaid means of relatively soft insulating material and providing a sealbetween said electrode and casing.

1l. In a mercury switch; a unitary metallic casing, having thesubstantial form of two concentric cylinders of differing internaldiameters, which casing serves as one of the electrodes of said switch;the outer end of the smaller diameter portion of said casing beingclosed at all times, and the outer end of the larger diameter portion ofsaid casing being open during the manufacture of said switch; anelectrode extending through said open end into said casing; a hollowcylindrical member of resilient insulating material, havingsubstantially the same diameter as the internal diameter of the largerportion of said casing, disposed about at least a portion of saidelectrode adjacent said open end, said member serving to position saidelectrode within said casing, to insulate said electrode from saidcasing, and to close said opening; and means for forcing said member ofresilient material toward the smaller portion of the casing and therebysubjecting it to a suicient deforming stress during the manufacture ofsaid switch to provide a gas-tight insulating seal between saidelectrode and said casing.

12. In a switch, a metallic casing having an opening therein, anelectrode extending into said casing through said opening, saidelectrode having a terminal portion for making electrical connection toan electrical circuit, a body of conducting fluid in the casing forcompleting the electric circuit through the switch, means forming a sealbetween said electrode and said casing including a member ofresilient'insulating material forced into tight engagement with saidelectrode and said casing, and a one-piece coating of an insulatingrubber material vulcanized on said casing and on said terminal portionand covering at least said opening through which the .electrode extendsand the portion of the casing adjacent thereto.

13. A mercury switch having a tubular metal shell comprising a main bodyportion closed at one end and a portion of larger diameter at the otherend terminating in a beaded edge portion which extends radially inwardlyto provide a retaining flange, a shoulder portion joining said main bodyportion and said portion of larger diameter, an insulator fitting withinsaid portion of larger diameter and held endwise in one direction bysaid shoulder portion of the shell and in the other direction of saidretaining iange,

an electrode mounted in said insulator, sealing means extending acrossthe area between said electrode and said shell, said retaining flangeapplying a force compressing said sealing means and forcing it intosealing engagement with said electrode and causing it to expand radiallyinto sealing engagement with said shell, and a body of mercury in saidshell which connects the main body portion of the shell and theelectrode across a portion of the insulator when the switch is tilted inone direction.

14. A mercury switch comprising a closed end tubular shell having anenlarged portion at the open end, an insert of insulation sealed in saidenlarged portion, said enlarged portion having its margin beaded overinwardly, a central electrode carried by said insert and communicatingat its inner end with the inside of the shell, a body of mercury in saidshell, a yielding gasket member extending over the entire area betweensaid central electrode and said shell, said yielding gasket member beingcompressed axially of said shell by said beaded-over margin so as to beforced into sealing engagement with said electrode and expanded radiallyinto sealing engagement with said shell.

15. In a mercury switch, a metal shell comprislng a first maincylindrical portion and a second portion of larger diameter joined tothe rst portion by a shoulder and having an inturned flange at its openend, a circular insulator disposed in said second portion of the shelland held against endwise displacement by said shoulder and said flange,an axially disposed electrode having a stem extending outside of .said

insulator, a body of mercury for making contact between the electrodeand the shell, an annular member of yielding insulating material aroundsaid stem and extending into engagement with said shell, and an annularmember of relatively rigid insulating material around said stem betweensaid member of yielding material and said inturned flange fordistributing the force applied by said inturned flange oversubstantially the entire area of said member of yielding material andforcing it into sealing engagement with both said electrode and saidshell.

16. In an inclosed mercury switch, the combination of a tubularcup-shaped shell having an inturned flange at its open end, a body ofinsulation adjacent the open end of the shell and having a shoulderedaperture, an electrode member carried in and closing the aperture insaid body, said electrodelmember having a stern and a head provided witha recess therein, a body of mercury for making contact with saidrecessed head and a part of said mercury being normally retained in saidrecess by said shoulder, an annular member of yielding insulatingmaterial around said stem and extending into engagement with said shell,and an annular member of relatively rigid insulating material aroundsaid stem between said member of yielding material and said inturnedflange for distributing the force applied by said inturned ange oversubstantially the entire area of said member of yielding material andforcing it into sealing engagement with both said electrode and saidshell.

MARTIN G. SA'I'EREN.

